Inside gauge



M. BARTHOLDY.

INSIDE GAUGE.

APPLICATION FILED DEc.z9,1921.

1 ,429,556, PatentedSept. 19, 1922.

5 E u: 4 a A /bi /a D a y V m -Tf22 c1 K @Ril Patented Sept. 19, 1922.

l UNITED STATES PATENT oFFlcE.

M '.AAXV BARTHOLDY, OF ESSEN, GERMANL, ASSIGNOR T0 `FRIED. KIR/UPP AKTIEN- GESELLSCHAFT, F ESSEN-ON-THERUHR, GERMANY.

INSIDE GAUGE.

To all whom #may concern.'

Be it known that I, MAX BARTHOLDY, residing at- Essen, Germany, a citizen of the German Republic, have invented a certain new and useful Improvement in Inside Gauges, of which the following is a specilication.l

This invention relates to inside gauges comprising two (gauge pins and two supporting pins, an has for its object to so construct gauges of this kind that they'are adapted for measuring holes of different diameters, without the iniuence of the supporting bolts upon correct measuring being thereby affected.

An inside screw-gauge embodying the invention is illustrated by way of example in the drawing, in which:

Fig. l is an axial longitudinal section of the gauge,

Fig. 2 is a similar section on line 2 2 of Fig. 1,I looking fromabove, with part of the gauge body in elevation,

Fig. 3 is a cross section on line 3-3 of Fig. 1, looking from the left, and,

Fig. 4 is a section through a detail.

' In the gauge body A is a longitudinally adjustable bolt B, screw-threaded at b1 to engage-an internal screw-thread a1 in the body.- The endof said bolt, projecting out of the bodyA, is slotted, so as to be eX- pansible by a screw C having a conical head c1, and thereby be rigidly connected to -a` kthimble D, which enclosesthe cylindrical end of the body A and is graduated in the usual way circumferentialily, the graduations (not shown) cooperating with a millimeter scale (also not shown) on the body A, to indicate the result of the measurement.

Against the end of the bolt B l ingwithin the body A, bears the end o a second bolt E.. The othei end of the bolt E isV provided with a conical surface e1, on which Aliest two balls F, as shown in Figs. l and 3, and on said 'balls-bear, underthe influence of springs G, the gauge pins H. The balls F are guided, on their sides away from the bolt E, in grooves a3, formed of plane' Surfaces a4 at an angle to each other, see Fig. 4. On their other sides the balls F liein vsemi-circular grooves a5. At rightangles to the pins H are mounted two supporting pins K, longitudinally movable against the pressure of springs J and held by the lat- I5 ter directly against the conical surface e1,

Application led Decemberl 29, 1921. .Serial No. 525,678.

see Fig. 2. The distance between the end surfaces cl of the pins K is slightly less 'than the distance between the measuringsurfaces h1 of the pins H', and the former lie within a circle which touches the latter and the dia-meter of which is equal to the distance between the surfaces h1, Fig. 3.

In use, the end of the gauge carrying the pins H and K is introduced into the bore to be measured?, the thimble D is turned, and with it the bolt B, which is advanced by the screw-threads al, b1 and transmits its longitudinal movement to the bolt E, the conical end e1 of which, consequently, forces the balls F and measuring pins H outwardly. u'But at the same time, the supporting pins K are displaced bythe cone e1, and by the vsame amount as the pins H, so that the distance between their ends kl'is always slightly less than the distance between the ends h1 of the pins H. The pins K, therefore, actas backing-up supports, no matter what the diameter of the hole is, an'd assist the operator in making correct measlurem'ents. The thimble D is turned until the pins H come to bear With their ends t'l on thewall of the bore. At this moment,

the measurement is completed.

`I11 consequence of the insertion of the balls F, guided in the grooves a3, between the 'conical surface e1 and the measuring pins H, the continued accuracy of the gauge is' insured. If said pins bore directly upon said surfacee1,'there would soon be manifest a wear of the guides of said pins H, which would result in making the measurements unreliable. It is. unnecessary to provide 'balls for the supporting pins K, also since vtheir end surfaces Il:1 have no direct effect supported by said body, a pair of relatively shorter supporting pins carried Lby said body and a member provided with a. coneshaped end adapted to displace said pins simultaneously during the measuring operation.

3. A gauge for measuring inside diameters comprising a body, supporting pins mounted on one end of said body, measuring pins mounted adjacent said supporting pins, an operating member provided with a conical head movable in said body, balls interposed between said measuring pins and the conical surface of said head, said supporting pins engaging directly upon said conical surface whereby said pins will be displaced upon a movement of said operating member.

4. A gauge for measuring inside diameters comprising a body, a longitudinally movable operating bolt, said bolt being pro vided with a head having a conical surface,

a pair of displaceable supporting pins mounted in one end of said body and engaging with their inner ends the conical surfacev of said head, a pair of measuring pins mounted in the said end of the body, balls interposed between the inner end of said measuring pins and the conical surface of said head whereby displacementof said bolt causes a simultaneous displacement of said supporting and measuring pin.

rllhe foregoing specification signed at Essen, Germany, this 29th day of November,

MaX nnnrnonnr. 

